An arginine regulated γ-guanidobutyrate ureahydrolase from tench liver (Tinca tinca L.)

Abstract

A γ-guanidobutyrate ureahydrolase isolated from tench liver has been characterized. Some of its physico-chemical properties like pH effect and thermal stability resemble those of arginases, however it shows some peculiarities that makes it different from arginases and other amidino hydrolases. Thus cation requirement is not as strong as in arginases, and the Km value for γ-guanido-butyric acid (230 ± 25 mM) is shifted to a lower value (45 ± 5 mM) by 5 mM arginine. The possible regulatory role of arginine on γ-guanidobutyrate ureahydrolase activity is discussed.